Air filter



FIG. 1 is a perspective view of an air filter showing our new design, configured horizontally;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a rear elevational view thereof;

FIG. 4 is a right side elevational view thereof;

FIG. 5 is a left side elevational view thereof;

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a bottom plan view thereof.

The broken lines shown in the drawings are for the purpose of illustrating portions of the article that form no part of the claimed design. 

CLAIM We claim the ornamental design for an air filter, as shown and described. 